What model PSU do you have or plan on using? The values are different on both. Also it is best to use a linear taper pot to make the adjustment. I use a 20 turn 50k pot to aquire the general range and then fine tune it from there.

i did that a few times too for fun, just tear out unnecessary components
and rearrange the output feedback loop to 13.8V and set up a current limit foldback at 10A,
now i have a 10A 13.8V CCCV car battery charger.

Z

Quote:

Originally Posted by Dreamglider

When i bought my multiplex easy star, it came with a 12v battery charger, i had a wall type psu rated at 4amps (what the charger needed) but it is to small the charger stopped the charging process as soon as it started.

Works nice but i did not use any load resistor on the +5v line but it works !

That particular model is for an SR6850HW4/M. It is the same as the Poweredge 6800 and is made in Thailand. So its the KD175 model. It also has the 3 internal fans. So that would mean 112Ω for 13.8v. This PS is pretty big but it pumps out lots of power. I'll update with more resistance values soon.

That particular model is for an SR6850HW4/M. It is the same as the Poweredge 6800 and is made in Thailand. So its the KD175 model. It also has the 3 internal fans. So that would mean 112Ω for 13.8v. This PS is pretty big but it pumps out lots of power. I'll update with more resistance values soon.

Thanks! I am pretty excited about the 6800 after reading your report. I will be getting it in a few days. I am sure I will be asking you some more questions when it comes in. Thanks again.

I've tweaked the voltage resistance values for the KD175. A value of 120Ω will set the voltage to 13.83v. It's a common resistor value and makes it easy to set the voltage permanently. So Brown-Red-Brown.

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I tried loads from 1.5 to 9 amps wired to the Right side +12V posts P5 & P7 and -12V to the P6 & P8 posts only.

The more amps I pull, the lower the +12 volts goes, from about +12.25 down to about 11.0 volts. Should I connect All Four +12v & four -12v posts together to share the load equally , in order to have it regulate the output voltage to +12.2 volts?

Also, if I were to connect an adjustable potentiometer between the C4 (+12V RMT SENSE) pin and the C5 (+12V RMT SENSE RETURN) pins at the load, shouldn't that allow me to adjust the output +12V to as high an output voltage as possible before the internal circuit design causes a high voltage fault?

(ie. If the sense voltage from the pot is 12.2 volts when the actual voltage across the load is 13.8 V)

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I don't think your supply should be dropping out of regulation like that. You can try connecting all four posts together. If this doesn't solve the problem you might have a bad PS. Just be sure to check that your pson and pskill are connected to ground.

Also, post 470 in this thread will answer all of your questions about voltage adjustment + some extra stuff.

7000245 Pinout

Hello Xandrios,

I am looking for the 5v output on the 7000245.

The nameplate says there is 2amps there but it is listed as 'sb', do you know what the 'sb' means?

[EDIT] I found 5v as shown in the attached image and loaded it to 1 amp with no appreciable voltage drop, still don't know what the 'sb' means. I had the wrong ground originally and couldn't find the 5v. There are probably more 5v pins that can be drawn from but a lot of 5v pins can't be loaded.

Yeah. Those are 2 of the primary 5vsb pins. Top row and 4 to the right is the other. With the power off, just check for full continuity between the pins you've already found and other pins. This will give you all the pins on that rail.

The sb stands for standby. It means that the 5v will be available in all modes of operation. Powered up, powered down(standby) and during a fault condition.

Bringing that up, this is the method I used to find the correct pins to power up this supply. It also works for a majority of PS units out there.

With power off and testing each pin to ground.

1. Exclude any pins that are common to each other(including ground pins). Usually these are the 3v and 5v rail pins. They also show the same resistance.

2. Exclude any open pins(pins with no resistance that don't connect to anything).

3. Exclude any pins with a value below 1k ohms and above 10k ohms. From my experience, I've found that the pson and pskill resistance usually falls between a 1k and 10k range.

With power on.

4. Exclude any pins that show no voltage.(pson and pskill are held partially TTL high or just not grounded. So they show some voltage on them).

This will usually leave between 4-6 pins.

Use a .5k ohm resistor on each of the individual remaining pins and connect each to ground. The power supply will usually power up at this point.

Disconnect one resistor at a time from ground.

If the PS remains on after a you disconnect a resistor from ground, then the remaining pins contain the pson and pskill. So keep it disconnected from ground.

If the power supply turns off, then the disconnected pin is either the pson or pskill. So reconnect it to ground.

Repeat this process until you find the pson and pskill pins.

In some cases the PS will turn on with a fault.

If this happens then disconnect one resistor(pin) at a time from ground to find the one that is causing the fault. Then continue with the process above to find the pskill and pson pins.

Even with the 32 pins on the Poweredge 6800 PS, I was able to narrow it down to just 5 pins before I even tried to power it up. It took just under 20 minutes.